Butterfly Glioma of the Corpus Callosum Mimicking Rapidly Progressive Dementia.

A butterfly-pattern, high-grade glioma involving the corpus callosum is an uncommon but highly aggressive brain tumour that may present with neuropsychiatric manifestations and mimic rapidly progressive dementia, leading to diagnostic delay. Disruption of frontal-callosal connectivity may produce behavioural and cognitive abnormalities resembling behavioural and psychological symptoms of dementia (BPSD), resulting in initial misdiagnosis. A 65-year-old postmenopausal woman presented with a two-week history of vomiting, progressive disorientation, generalized weakness, irrelevant speech, cognitive decline, and bladder and bowel dysfunction. She had previously been treated for acute-onset dementia with BPSD using donepezil and memantine without prior neuroimaging. Neurological examination revealed asymmetric pyramidal signs, rigidity, and bilaterally constricted pupils. Arterial blood gas analysis showed respiratory alkalosis with hypocalcaemia, and urine culture isolated extended-spectrum beta-lactamase (ESBL)/AmpC-producing Klebsiella aerogenes. Contrast-enhanced MRI demonstrated a greater than 65 × 61 mm solid-cystic heterogeneously enhancing mass involving the genu of the corpus callosum with bifrontal extension and perilesional oedema, favouring a radiologically suspected high-grade glioma involving the corpus callosum. A stereotactic biopsy was planned for histopathological confirmation. The patient received corticosteroids, anti-epileptics, antibiotics, and supportive treatment, with subsequent clinical improvement. This case underscores the importance of early neuroimaging in atypical dementia presentations, especially when focal neurological deficits or signs of raised intracranial pressure are present. Histopathological confirmation remains essential for definitive diagnosis and treatment planning.